Power-operated percussive tool.



nr i' salare aan nic.

'CHARLES H. HAESELER, OF PHILADELPHIA, PENNSYLVANIA.

POWER-OPERATED PERCUSSIV TOOL.

i,ooalsta.

Specification of Letters Patent.

Patenten oet. 3, v1an.

Application led March 22, 1911. Serial No. 616,110.

ica, anda resident of Philadelphia, county of Philadelphia, and State of Pennsylvania, have invented certain new and useful Improvements in Power-Operated Percussive Tools, of which the following is a specification, 'reference being had to the accompanying drawings, forming a part thereof.

My invention relates to power operated percussive tools such as rock drills, mining machines, power hammers, pile drivers and the like, the operation of which is effected by elastic motive fluid under pressure altervnately admitted into a working cylinder upon opposite sides of a reciprocating piston freely mounted therein.

In copending applications Serial Number 578,149 filed August 20, 1910, and Serial Number 612,186 filed March 4, 1911, I have disclosed' novel means for cushioning 'the working piston upon the return stroke, together with means for augmenting the force of the blow imparted upon the forward or working stroke, such r'r'ieans not only tending to increase the speed of movement of the piston butto decrease the amount of motive fluid consumed; and my present invention relates to a specific construction of mechanism adapted to effect' this result.

In order that my inyention may be thoroughly understood, I 'will now proceed to describe an embodiment'thereof having reference to the accon'ipanying drawing which comprises a view in central longitudinal section. through a power rock drill constructed in. accordance with my invention, and will then point out the novel features in claims.

The` rock drill illustrated comprises in general a main working cylinder 5, a reciprocating piston 6 therein, a distributing valve 7 for admitting and exhaustin motive fluid to and from the cylinder below and' above the piston, and rotating mechanism by whicl'i step bystep movements of lrotation are imparted to the piston. The valve 7 is of the piston type and is operated inA one direction or the other by fluid under pressure, at about the time the piston vreaches the end of its stroke in either direcrifle bar are permitted in one direction but prevented in the other, and a nut 11 secured in the upper end of the piston 6 and" fitted to the said rifle bar. 'The piston 6 vhas a4 cylindrical cavity 12 ltherein which receives the forward end of the rifle bar 8, and the said forward end of the rifle bar has affixed thereto, or formed Vas a part thereof, a small piston 13 which is fitted to the said cylindrical cavity 12, as will readily be seen by reference to the drawing.

In the normal operation of the tool, elastic motive fluid such as air or steam under pressure, is first admitted-behind the piston to move the same forward, the workin space in the main 'cylinder in front of the main piston being at such time opened t0 exhaust; then as the piston reaches t-he end of its forward stroke motive fluid is admitted in front of the piston to drive the same backward, previously employed motive fluid at the back of the piston being permitted at such times to pass to exhaust. In the forward movement of the piston the ratchet 4and pawl mechanism 10 permits the rifle revolution by means of the coaction of the inclined grooves therein with the complementary portions in the nut 11, while upon the rearward or return movement of the pis- 'ton 6 the ratchet and pawl mechanism holds the rifle bar stationary and a partial movement of rotation is imparted by therile bar to the piston.

The main piston 6 is provided at the forward end with a channel 14, the forward end of which opens directly into the space in the main work-ing cylinder 5 in front of the piston 6, while the-rear end communicates through a crossv passage 15 with the cylindrical cavity 12 in front of the cushioning pistonl 13 when the main piston is in its forward position. When the main piston is in its forward position there will be free admission of motive fluid sure from the forward end ofthe main cylindcr, through the channel 14 and cross passage 15, to the cylindrical cavity 12. As the main piston moves backward the cross Apassage 15 will be roverridden by the cushioning piston v`13v whereby the remaining motive fluid in the cavity 12' will be locked up therein so that throughout the remainder of the rearward'movement of the main piston such motive Huid will be compressed.

under pres- 'throughout which the motive fluid is compressed in the cylindrical cavity 12,: will de? pend uponthe position of the cross passage 15, which cross passage maybe made to enter the cavt 12 nearer to, or farther from, the cushioning piston 13 'when the main piston is ln its forward position, as is shown in the drawing, as may be desired. If it enters the cylindrical cavity at a point close Vto the cushioning piston, when the main piston is in its forward position, then the motive fluid will be compressed during' the entire return movement of the main piston. As shown the main piston is permitted tormove throughout the first part of-its return movement before such compression takes place in order that theinitial portion of :the return movement shall not be opposed by the compression of the motive iiuid. In addition to preventing the return movement lbeing opposed by the worlr done in compressing motive. Huid, li' have also shown a relief passage 16 by which even the tension of the motive fluid may itself be released atv the time of the initial rear ward movement of the main piston. The motive fluid in the cavity 12 will discharge through this channel 16'to the rear of the,v

cushioning piston 13 whence it will pass' between the rifle bar Sand the nut 10 to the rear of the main piston 6, and so to exhaust. The distance between the point at which the passage 16 enters the cylindrical cavity 12 and the frontl end of the cushioning piston 13 when the main pistonis in its most forward position is quite shortso that very quicklyiafter its first. rearward movement the port opening to such relief passage will override the cushioning piston 13 and escape cut-off therethrough. Preferably there is a short distance between the point at which the relief passage 16 enters the cavity 12 and the point at which the cross-passage 15 enters the cavity 12 so that in the movement of the main piston from the point at which the port of the passage 1G is closed up, to the point at which the cross-passage 15 is closed, motive fluid will be entering through the channel 111-. and the cross-passage 15 into the cavity 12 to build up pressure therein, to nearly, if not quite the full motive fluid pressure. In the remaining part of the movement of the piston 13 this motive fluid,l `which will have been entrapped directly the cross-passage le was confient may also be varied to suit different conditions and requirements, it being understood that in any event there mustbe no large channel such as will permit free or unlimited discharge of motive fluid from the main cylinder in front of the main piston. As shown the channel 13 is of very small capacity and this is the preferred construc- The relative cross-sectional areas of the passages tion, the passage being in the nature of a bleeding passage such as will supply the cavity 12 without appreciably lowering the pressure in the main cylinder in front of the main piston.

1. in an elastic lfluid operated percussive tool, the combination with a main cylinder and a percussive piston freely mounted therein and having a cylindrical cavity projecting inward from the rear end thereof7 of a cushioning piston mounted irI the cylindrical cavity and held against relative longitudinal movement therein, and means for admitting elastic motive fluid under pressure to the cylinder, the said percussion piston being provided with a channel the rear end of which enters the cylindrical cavity and the forward end of which is in open'free communication with the main cylinder in front of the percussion piston'. the rear end of the said channel being in a position fo be overridden by the cushioning piston in the rearward movement of the main piston.

2. 1n a rock drill, the combination with a main cylinder and a percussion piston freely mounted therein and vhaving a cylindrical cavity projecting inward from the rear end thereof, of a longitudinally stationary bar carried by therearhead of the main cylinder and projecting forwardly into the said cylindrical cavity, a cushioning piston carried by the forward end of the said bur and fitted to the said cylindrical cavity, and means for admitting elastic motivo fluid under. pressure to the cylinder, thesaid percussion pis-v ton being provided with a channel, the rear end of which enfers the cylindrical cavity and the forward end of' which is in open free communication with the main cylinder in front of the percussion piston, the rear end of the said channel being in a position to be over-ridden by (he cushioning piston in the rearward movement of the main piston.

3. In an elastic fluid operated percussive tool, the combination with a main cylinder nuocere and a percussion piston freely mounted theren in and having a cylindrical cavity project ing inward from the rear end thereof, of a y cushioning piston mounted in the cylindrical cavity and held against longitudinal inovement therein, and means for admitting elastic motive iiuid under pressure to the cylinder, the said percussion piston being provided with a channel the rear end ot which enters the said cylindrical cavity and the forward end of which is in open communica" tion with the main cylindef in front of the piston, and with another' channel the torward end of which enters Jthe cylindrical cavity and the' rear end of which communi- 1a-tes with the cylinder to the rear of the percussion piston, the for fard end of the second said ychannel and the rear end of the first said channel being arranged to 'oe overridden by the cushioning?T piston in 'the rearward movement ot' the main piston.

4. ln an elastic fluid operated percussive tool, the combination with a main cylinder and a percussion piston freely mounted therein and having a cylindrical cavity projecting inward :from the rear end thereof, of a cushioning piston mounted in the cylindrical cavity and held against longitudinal movement therein, and means for admitting' elastic motive fluid under pressure to the cylinder, the said percussion piston being' provided with a channel the rear end ot which enters the said cylindrical cavity and the forward end of which is in open coin1nunication with the main cylinder in front of 'the piston, and with another channel the forward end of which enters the cylindrical. cavity and thc rear end of which communicates with the cylinder; to the rearof the percussion piston, the forward end of the second said channel and the'rear end of the first said channel being arranged to be successively.overridden by the cushioning-,piston in the rearward movement ot the main. piston. l

5. ln a rock drill, the combination with a main cyliiider and a percussion piston freely 'mounted ltherein and having;` a cylindrical cavity projecting inward from ti rear end thereof, of a longitudinally stationh .ary har carried oy the rear head ofthe main cylinder and nroiecting' forwardly into the said cylindrical cavity,` a cushioning piston carried by the iorward end of 'the said har and fitted to the said cylindrical cavity, and

means for admitting elastic motive iiuid under pressure to the cylinder, the said percussion piston being provided with a channel the rear end of which enters the said cylindrical cavity and the forward end ot" which is in open coinn'iunication with the-main cylinder in front of the piston, and with another channed the forward end of which enters 'the cylindrical cavity and the rear end ot' which communicates with the cyl- 65 inder to the rear of the percussion piston, the lorw rd end oli the second said channel` and the rcarend of the first said channel being arranged to 'ce Gvenridden hy the cushioning piston in the rearward movement of the 7o main piston.

6. ln a roclr'drill, aI main cylinder and a percussion piston freely mounted therein and having acylindrical cavity projecting Yinward from the 75 rear end the-rect, of a longitudinally stationary har carried hy the rear head of the main -cylinder and projecting forwardly into the said cylindrical cavity, a cushioning piston carried by the forward end of the said bar and fitted to the said cylindrical cavity, and means for admitting elastic motive luid under pressure to the cylinder', the said percussion piston being provided with Lohannel the rear end of which enters the said cylindrical cavity and the forward end of which is in open communication with vthe main cylinder in front ot' the piston, and with another channel the forward end of which enters the cylindrical cavity and the rear end of which communicates with the cylinder to the rear of the percussion piston, the forward end of the second said channel and the rear end of 'the irst said channel heine; arranged to loe successively over-ridthe conihination with 

